New York's Heroes (A Percy Jackson/Avengers Crossover)

First, it was aliens.
Then it was Titans.
And just this last summer, it was Romans.
Poor, poor New York. A apocalypse about everyday, along with hidden heroes and plotting enemies roaming the busy streets and taking the subway.
And now, two forces of heroes are going to meet, destroying a couple buildings, causing explosions, possibly harming innocents....
(Disclaimer for the whole story: PJO/HoO= Rock Riordan, Marvel=Stan Lee/any other character creator in the Marvel universe)